As you are leaving from your previous ordeal, you notice that another convict is being taken to a jail cell. As you watch the guard and the convict go to the cell, they start talking.
"You do realize your rights, right?" says the guard.
The convict replies, "The judge said something strange, but I didn't understand it. What was it?"
"You are free to go anytime you like," declares the guard, "as long as you fulfill the required conditions. In your case, your door is secured with a ten-digit lock. If you can guess the right number, you are free to go."
"That's easy," says the prisoner. " I can just keep guessing numbers until I guess the right one."
"Even so," says the guard, "it would take you a hundred years to find the right number at the rate of one per second. Of course, you can always look for the hints we give you." He then points at you and proceeds to tell the new prisoner about your imprisonment.
"In addition to the normal...amenities, you have a desk and a scientific calculator. Good luck." The guard walks away.

You stand there for a few minutes before you realize that you can go. As you turn to leave, you notice that the new prisoner is walking up behind you.
"Wow, this place is great!" he says. "I only had to input one number!"

This slowing of the earth's rotation is the reason for the leap seconds described in comments 6 and 7. They are irregular, rather than every 18 months, and can occur at the end of either June or December. And more specifically it is something of the order of one second per year per century (as it's a negative angular acceleration), as the interpretation of a second in this sense is 1/86,400 of a rotation.